Fascinated with surface mounted parts

[Rene]

I recently had a PCB made and on it I soldered a couple of surface mounted
parts, no big deal since the parts were few and relatively big.

After experiencing doing this, I took one of my old motherboards and took a
closer look at it, I was really amazed at the size of some of the
components. They are so small and so many, I could not help to wonder how
they put all these parts together so neatly and fast.

Does anybody know of a web site that shows the assembly process for things
like computer motherboards? I am just fascinated by it and would like to
know how they do it, just for my own amusement.

Thank you

 

[TCS]

On Sat, 15 May 2004 03:15:26 GMT, Rene <nospam@nospam.nospam> wrote:

I recently had a PCB made and on it I soldered a couple of surface mounted
parts, no big deal since the parts were few and relatively big.

After experiencing doing this, I took one of my old motherboards and took a
closer look at it, I was really amazed at the size of some of the
components. They are so small and so many, I could not help to wonder how
they put all these parts together so neatly and fast.

trained baby monkeys

 

[Robert Baer]

Rene wrote:

I recently had a PCB made and on it I soldered a couple of surface mounted
parts, no big deal since the parts were few and relatively big.

After experiencing doing this, I took one of my old motherboards and took a
closer look at it, I was really amazed at the size of some of the
components. They are so small and so many, I could not help to wonder how
they put all these parts together so neatly and fast.

Does anybody know of a web site that shows the assembly process for things
like computer motherboards? I am just fascinated by it and would like to
know how they do it, just for my own amusement.

Thank you

All done by machine, where the quantity of boards is sufficent.
Look in the DigiKey catalog and find one of the surface mount parts.
Note they mention "cut tape" and "reel".
Instead of a large DIP part being slid into a tube by machine, the
small parts are placed into the cavity of the tape by machine (small
vacuum needle used to pick and place), and then the cover tape is stuck
on top to seal the part inside.
Solder paste is put on the exposed copper pads, and there may or may
not be a spot of adhesive previously put on the PCB to hold the part.
At the assembly house, the rolls of tapes (remember, a lot of
different parts) are mounted on handlers that can open the tape and use
a similar vacuum needle to pick up a part, move to the proper position
on the PCB, and place it.
The assembly either goes (via belt) past heat lamps, or in some
(unknown manner by me) past a solder wave machine.

Undoubtedly others more versed in the methodology can give a better
and more comprehensive explaination and/or references.

 

[Active8]

On Sat, 15 May 2004 08:16:50 GMT, Robert Baer wrote:

Rene wrote:

I recently had a PCB made and on it I soldered a couple of surface mounted
parts, no big deal since the parts were few and relatively big.

After experiencing doing this, I took one of my old motherboards and took a
closer look at it, I was really amazed at the size of some of the
components. They are so small and so many, I could not help to wonder how
they put all these parts together so neatly and fast.

Does anybody know of a web site that shows the assembly process for things
like computer motherboards? I am just fascinated by it and would like to
know how they do it, just for my own amusement.

Thank you

All done by machine, where the quantity of boards is sufficent.
Look in the DigiKey catalog and find one of the surface mount parts.
Note they mention "cut tape" and "reel".
Instead of a large DIP part being slid into a tube by machine, the
small parts are placed into the cavity of the tape by machine (small
vacuum needle used to pick and place), and then the cover tape is stuck
on top to seal the part inside.
Solder paste is put on the exposed copper pads, and there may or may
not be a spot of adhesive previously put on the PCB to hold the part.
At the assembly house, the rolls of tapes (remember, a lot of
different parts) are mounted on handlers that can open the tape and use
a similar vacuum needle to pick up a part, move to the proper position
on the PCB, and place it.

Some PCB footprints will have a place outline which defines the
extent of the placement head so it doesn't mash an adjacent part.

Fiducials are registration marks on the board which provide an
optical reference for the placement machine to place parts. They're
typically placed near larger parts. They also provide a means for
the placement machine to recalibrate itself against cumulative
error.

A little placement (read alignment) error here and there, cumulative
or otherwise, is not a problem as long as the pins are on the
correct pads. The surface tension of the solder paste as it reflows
will pull the part into alignment.

The assembly either goes (via belt) past heat lamps, or in some
(unknown manner by me) past a solder wave machine.

that's where the adhesive comes into play. The board is inverted and
wave soldered - through-hole parts would typically be on the
opposite side and therefor simultaneously wave soldered with the smd
parts. The parts must be lined up so that the pins pass throught the
wave inline, not broadside, otherwise the "leeward side pins" would
be in the shadow area (shadow zone ) of the package - IOW, the
wave would be shadowed or blocked by the pkg.

Undoubtedly others more versed in the methodology can give a better
and more comprehensive explaination and/or references.

"Printed Circuits HAndbook." Coombs Jr. is one ref on everything
PCB. but since OP just needs amusement, that might be a bit much.
--
Best Regards,
Mike

 

[Rich Grise]

"Rene" <nospam@nospam.nospam> wrote in message
news:iXfpc.51742$xw3.3131072@attbi_s04...

I recently had a PCB made and on it I soldered a couple of surface mounted
parts, no big deal since the parts were few and relatively big.

After experiencing doing this, I took one of my old motherboards and took
a
closer look at it, I was really amazed at the size of some of the
components. They are so small and so many, I could not help to wonder how
they put all these parts together so neatly and fast.

Does anybody know of a web site that shows the assembly process for things
like computer motherboards? I am just fascinated by it and would like to
know how they do it, just for my own amusement.

Thank you


I found

http://www.google.com/search?hl=en&ie=UTF-8&q=pick+place+machine
to be kinda fun.

You're welcome.

Cheers!
Rich